Projection system and method for selecting image capturing number for image blending

ABSTRACT

A projection system and a method for selecting an image capturing number for image blending are provided. Multiple projection devices are driven one-by-one to project a pattern; multiple image capturing devices are driven to capture the pattern projected by each projection device, so as to obtain multiple image capturing results corresponding to the image capturing devices. Finally, at least one of the image capturing devices is selected to serve as an image capturing source for image blending based on the image capturing results. An image capturing range is identified through projected patterns, and an effective range is calculated and then selected for use, which is used for calculations required for automatic blending, so as to avoid a problem of being unable to maintain blending and merging due to environmental influences or failure of the image capturing device when performing image recognition and calculation required for automatic blending and merging.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China Application No.202011457078.8, filed on Dec. 11, 2020. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND Technical Field

The invention relates to a projection system and a method, andparticularly relates to a projection system and a method for selectingan image capturing number for image blending.

Description of Related Art

Projection blending is to integrate a plurality of projectors to merge aprojection image into a display area such as an extending wall surface,a ring-like, arc, irregular wall surface, etc. Selection of theprojectors is most important, since without an edge blender, there is aproblem of image overlap where projection ranges of two projectors areintersected, resulting in increased brightness and blurred signals inthe overlapped area. Edge blending technology is to perform edge overlapon images projected by a group of projectors, and display a seamless,brighter, integral image with higher-resolution by using the blendingtechnology, so that the projection image may have image quality likethat of an image projected by one projector. In order to realizeautomatic blending, cameras are used to photograph the projection image,so as to use the projection image to perform image recognition andcalculation required for automatic image blending.

The information disclosed in this Background section is only forenhancement of understanding of the background of the describedtechnology and therefore it may contain information that does not formthe prior art that is already known to a person of ordinary skill in theart. Further, the information disclosed in the Background section doesnot mean that one or more problems to be resolved by one or moreembodiments of the invention was acknowledged by a person of ordinaryskill in the art.

SUMMARY

The invention is directed to a projection system and a method forselecting an image capturing number for image blending, which avoid aproblem of being unable to maintain blending and merging due toenvironmental influences or failure of an image capturing device whenperforming image recognition and calculation required for automaticblending.

The invention provides a projection system including a plurality ofprojection devices, a plurality of image capturing devices, and aprocessor. The processor is coupled to the projection devices and theimage capturing devices. The processor is configured to drive theprojection devices one-by-one to project a pattern, drive the imagecapturing devices to capture the pattern projected by each of theprojection devices, so as to obtain a plurality of image capturingresults corresponding to the image capturing devices, and select atleast one of the image capturing devices to serve as an image capturingsource for image blending based on the image capturing results.

The invention provides a method for selecting an image capturing numberfor image blending, which includes following steps: driving a pluralityof projection devices one-by-one to project a pattern; driving aplurality of image capturing devices to capture the pattern projected byeach of the projection devices, so as to obtain a plurality of imagecapturing results corresponding to the image capturing devices; andselecting at least one of the image capturing devices to serve as animage capturing source for image blending based on the image capturingresults.

Based on the above description, according to the invention, the numberof images obtained by the image capturing devices by capturing theprojected patterns is reduced, so as to improve a speed of an imagecapturing process, and avoid the problem of being unable to maintainblending due to environmental influences or failure of the imagecapturing devices when performing image recognition and calculationrequired for automatic blending.

Other objectives, features and advantages of the present invention willbe further understood from the further technological features disclosedby the embodiments of the present invention wherein there are shown anddescribed preferred embodiments of this invention, simply by way ofillustration of modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a block diagram of a projection system according to anembodiment of the invention.

FIG. 2 is a flowchart illustrating a method for selecting an imagecapturing number for image blending.

FIG. 3 is a flowchart illustrating a method for obtaining an imagecapturing result according to an embodiment of the invention.

FIG. 4A to FIG. 4I are schematic diagrams of image capturing resultsaccording to an embodiment of the invention.

FIG. 5A and FIG. 5B are schematic diagrams of activating a backup deviceaccording to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the invention may be practiced. In this regard, directionalterminology, such as “top,” “bottom,” “front,” “back,” etc., is usedwith reference to the orientation of the Figure(s) being described. Thecomponents of the present invention can be positioned in a number ofdifferent orientations. As such, the directional terminology is used forpurposes of illustration and is in no way limiting. On the other hand,the drawings are only schematic and the sizes of components may beexaggerated for clarity. It is to be understood that other embodimentsmay be utilized and structural changes may be made without departingfrom the scope of the present invention. Also, it is to be understoodthat the phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless limited otherwise, the terms“connected,” “coupled,” and “mounted” and variations thereof herein areused broadly and encompass direct and indirect connections, couplings,and mountings. Similarly, the terms “facing,” “faces” and variationsthereof herein are used broadly and encompass direct and indirectfacing, and “adjacent to” and variations thereof herein are used broadlyand encompass directly and indirectly “adjacent to”. Therefore, thedescription of “A” component facing “B” component herein may contain thesituations that “A” component directly faces “B” component or one ormore additional components are between “A” component and “B” component.Also, the description of “A” component “adjacent to” “B” componentherein may contain the situations that “A” component is directly“adjacent to” “B” component or one or more additional components arebetween “A” component and “B” component. Accordingly, the drawings anddescriptions will be regarded as illustrative in nature and not asrestrictive.

FIG. 1 is a block diagram of a projection system according to anembodiment of the invention. Referring to FIG. 1, the projection systemof the embodiment includes M projection devices 110-1 to 110-M, N imagecapturing devices 120-1 to 120-N, and a processor 130. Here, a number ofthe projection devices and a number of the image capturing devices arenot limited, as long as there are at least two projection devices and atleast two image capturing devices, and the number of the projectiondevices M and the number of the image capturing devices N may be thesame or different.

In terms of setting, the image capturing devices 120-1 to 120-N may berespectively installed on each of the projection devices 110-1 to 110-M.For example, one projection device is provided with one image capturingdevice. The processor 130 is, for example, installed in an independentelectronic device, and is coupled to the projection devices 110-1 to110-M and the image capturing devices 120-1 to 120-N through a wired orwireless manner, so as to drive the projection devices 110-1 to 110-Mand the image capturing devices 120-1 to 120-N to operate, and adjustparameters of the projection devices 110-1 to 110-M after performingimage recognition and analysis.

The processor 130 is, for example, a central processing unit (CPU), agraphic processing unit (GPU), a physics processing unit (PPU), aprogrammable microprocessor, an embedded type control chip, digitalsignal processor (DSP), application specific integrated circuits (ASIC)or other similar devices. In an embodiment, the processor 130 may be animage blending processing device. The electronic device also includes astorage device, which may be implemented by any type of a fixed orremovable random access memory, a read-only memory, a flash memory, asecure digital card, a hard drive or other similar devices or acombination of these devices. One or a plurality of program instructionsare stored in the storage device, and the processor 130 executes theprogram instructions to implement a following method for selecting animage capturing number for image blending.

FIG. 2 is a flowchart illustrating a method for selecting an imagecapturing number for image blending. Referring to FIG. 1 and FIG. 2, instep 5205, the processor 130 drives the projection devices 110-1 to110-M one-by-one to project a pattern. The pattern, for example, has aplurality of grid points on left and right sides.

In addition, in step S210, the processor 130 drives the image capturingdevices 120-1 to 120-N to capture the patterns projected by each of theprojection devices 110-1 to 110-M, so as to obtain a plurality of imagecapturing results corresponding to each of the image capturing devices120-1 to 120-N. Here, after one of the projection devices projects apattern, the processor 130 may drive the image capturing devices 120-1to 120-N to respectively or simultaneously photograph the projectedpattern.

In step S215, the processor 130 selects at least one of the imagecapturing devices 120-1 to 120-N to serve as an image capturing sourcefor image blending based on the image capturing results. The processor130 may identify a grid point number of the grid points included in eachimage capturing result and a grid point position of each grid point, andselect at least one of the image capturing devices 120-1 to 120-N toserve as the image capturing source for image blending based on the gridpoint number and the grid point positions. A photographing range of theselected image capturing device covers the most grid points.

Since when all of the projection devices 110-1 to 110-N projectpatterns, a problem of pattern overlap occurs, the processor 130 drivesone projection device to project a pattern at a time, and each time whena pattern is projected, at least one image capturing device is used tocapture an image. Another example is provided below to describe an imagecapturing sequence. It should be noted that a sequence that theprojection device projects the patterns may be determined by theprocessor 130 or set by a user, which is not necessarily a settingsequence of the projection devices.

FIG. 3 is a flowchart illustrating a method for obtaining an imagecapturing result according to an embodiment of the invention. Referringto FIG. 3, in step S305, an i^(th) projection device is driven toproject a pattern, where an initial value of i is 1. Then, in step S310,a j^(th) image capturing device is driven to capture the projectedpattern, where an initial value of j is 1. In addition, in step S315,i=i+1, so as to subsequently drive a next projection device to project apattern. Then, in step S320, it is determined whether all of theprojection devices have completed projections. For example, when Mprojection devices are provided, it is determined whether i is greaterthan M. If there are still projection devices that have not completedprojections (i is not greater than M), the flow returns to step S305;and if all of the projection devices have completed projections (i isgreater than M), in step S325, j=j+1, so as to subsequently drive a nextimage capturing device to capture the projected pattern.

Then, in step S330, it is determined whether all of the image capturingdevices have completed image capturing. For example, when N imagecapturing devices are provided, it is determined whether j is greaterthan N. If there are still image capturing devices that have notcompleted image capturing (j is not greater than M), the flow returns tostep S305. If all of the image capturing devices have completed imagecapturing (j is greater than M), in step S335, an image capturing resultis obtained.

For example, the processor 130 drives the projection device 110-1 toproject a pattern, and drives the image capturing device 120-1 toperform image capturing. Then, the processor 130 drives the projectiondevice 110-2 to project a pattern, and drives the image capturing device120-1 to perform image capturing. Deduced by analogy, the projectiondevice 110-M is driven to project a pattern, and the image capturingdevice 120-1 is driven to perform image capturing. Namely, the imagecapturing device 120-1 respectively performs image capturing on thepatterns projected by the projection devices 110-1 to 110-M. Thereafter,the projection devices 110-1 to 110-M are re-driven to project patterns,and the image capturing device 120-2 respectively performs imagecapturing on the patterns projected by the projection devices 110-1 to110-M. Deduced by analogy, until the image capturing device 120-Nrespectively performs image capturing on the patterns projected by theprojection devices 110-1 to 110-M.

In other embodiments, it is also possible to drive all of the imagecapturing devices 120-1 to 120-N to perform image capturing at the sametime each time after a pattern is projected by one projection device. Inanother embodiment, a sequence that the projection devices projectpatterns and the image capturing devices perform image capturing may bedesigned differently according to actual conditions. For example, a partof the projection devices may be driven to project patterns, and a partof the image capturing devices are driven to perform image capturing,and then another part of the projection devices are driven to projectpatterns, and another part of the image capturing devices are driven toperform image capturing.

FIG. 4A to FIG. 4I are schematic diagrams of image capturing resultsaccording to an embodiment of the invention. In the embodiment, threeprojection devices 110-1 to 110-3 and three image capturing devices120-1 to 120-3 are taken as examples for description, and four gridpoints are set at four corners to serve as a projected pattern, but theprojected pattern is not limited to this. Based on positions where theprojection devices 110-1 to 110-3 are installed, projection images(411-413, 421-423, 431-433, 441-443, 451-453, 461-463, 471-473, 481-483,491-493) projected by the projection devices 110-1 to 110-3 may haveoverlapped portions (shown by shaded blocks in FIG. 4A-FIG. 4I).Accordingly, in case that all of the projection devices projectpatterns, the problem of pattern overlap occurs.

Therefore, in the embodiment, a following configuration is set: theprocessor 130 drives one projection device at a time to project apattern, and a projection sequence thereof is, for example, theprojection device 110-1, the projection device 110-2, the projectiondevice 110-3, and one image capturing device is used to perform imagecapturing each time when the projection is performed. Each of the imagecapturing devices 120-1 to 120-3 may respectively perform imagecapturing on the patterns projected by the projection devices 110-1 to110-3 to obtain image capturing results A1-A9. Therefore, in terms ofthree projection devices and three image capturing devices, 9 (3×3)image capturing results are finally obtained.

First, referring to FIG. 4A-FIG. 4C, the processor 130 drives the imagecapturing device 120-1 to respectively perform image capturing on thepatterns projected by the projection devices 110-1 to 110-3. Then,referring to FIG. 4D to FIG. 4F, the image capturing device 120-2 isdriven to respectively perform image capturing on the patterns projectedby the projection devices 110-1 to 110-3. Thereafter, referring to FIG.4G to FIG. 4I, the image capturing device 120-3 is driven torespectively perform image capturing on the patterns projected by theprojection devices 110-1 to 110-3.

In FIG. 4A, the processor 130 drives the projection device 110-1 toproject a pattern, so as to obtain a projection image 411. At this time,since the projection devices 110-2 and 110-3 do not project patterns,corresponding projection images 412 and 413 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-1 toperform image capturing to obtain an image capturing result A1. In FIG.4B, the processor 130 drives the projection device 110-2 to project apattern, so as to obtain a projection image 422. At this time, since theprojection devices 110-1 and 110-3 do not project patterns,corresponding projection images 421 and 423 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-1 toperform image capturing to obtain an image capturing result A2. In FIG.4C, the processor 130 drives the projection device 110-3 to project apattern, so as to obtain a projection image 433. At this time, since theprojection devices 110-1 and 110-2 do not project patterns,corresponding projection images 431 and 432 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-1 toperform image capturing to obtain an image capturing result A3.

In FIG. 4D, the processor 130 drives the projection device 110-1 toproject a pattern, so as to obtain a projection image 441. At this time,since the projection devices 110-2 and 110-3 do not project patterns,corresponding projection images 442 and 443 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-2 toperform image capturing to obtain an image capturing result A4. In FIG.4E, the processor 130 drives the projection device 110-2 to project apattern, so as to obtain a projection image 452. At this time, since theprojection devices 110-1 and 110-3 do not project patterns,corresponding projection images 451 and 453 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-2 toperform image capturing to obtain an image capturing result A5. In FIG.4F, the processor 130 drives the projection device 110-3 to project apattern, so as to obtain a projection image 463. At this time, since theprojection devices 110-1 and 110-2 do not project patterns,corresponding projection images 461 and 462 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-2 toperform image capturing to obtain an image capturing result A6.

In FIG. 4G, the processor 130 drives the projection device 110-1 toproject a pattern, so as to obtain a projection image 471. At this time,since the projection devices 110-2 and 110-3 do not project patterns,corresponding projection images 472 and 473 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-3 toperform image capturing to obtain an image capturing result A7. In FIG.4H, the processor 130 drives the projection device 110-2 to project apattern, so as to obtain a projection image 482. At this time, since theprojection devices 110-1 and 110-3 do not project patterns,corresponding projection images 481 and 483 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-3 toperform image capturing to obtain an image capturing result A8. In FIG.4I, the processor 130 drives the projection device 110-3 to project apattern, so as to obtain a projection image 493. At this time, since theprojection devices 110-1 and 110-2 do not project patterns,corresponding projection images 491 and 492 thereof are blank. Inaddition, the processor 130 drives the image capturing device 120-3 toperform image capturing to obtain an image capturing result A9.

After obtaining the image capturing results A1-A9, the processor 130identifies the grid point numbers of the grid points included in theimage capturing results A1-A9 and the grid point positions of the gridpoints based on the image capturing results A1-A9. Furthermore, theprocessor 130 determines projection ranges of the projection devicescovered by the photographing range of each of the image capturingdevices 120-1 to 120-3 based on the grid point positions in the imagecapturing results A1-A9. In this way, the grid point numbers and theprojection ranges covered by the photographing range of each of theimage capturing device 120-1 to 120-3 are listed in Table 1.

TABLE 1 Image Image Grid Covered capturing capturing point Covered gridpoint device result number projection ranges number 120-1 A1 4Projection device All  6 110-1 A2 2 Projection device Partial 110-2 A3 0Projection device None 110-3 120-2 A4 4 Projection device All 110-1 A5 4Projection device All 10 110-2 A6 2 Projection device Partial 110-3120-3 A7 2 Projection device Partial 110-1 A8 4 Projection device All 10110-2 A9 4 Projection device All 110-3

Referring to Table 1, the grid point numbers and the projection rangescovered by the photographing ranges of the image capturing devices120-1, 120-2, 120-3 may be identified based on the image capturingresults A1-A3, the image capturing results A4-A6, and the imagecapturing results A7-A9.

Based on the above description, the processor 130 selects the imagecapturing sources for image blending from the image capturing devices120-1 to 120-3 based on the grid point number and the grid pointpositions of the grid points covered by the photographing range of eachof the image capturing devices 120-1 to 120-3. In addition, otherunselected image capturing devices are used as backup image capturingsources.

For example, regarding the patterns (including 4 grid points) projectedin FIG. 4A to FIG. 4I, if the grid point number of the grid pointscovered by one of the image capturing devices is equal to 12, itrepresents that each image capturing result corresponding to the threeprojection devices 110-1 to 110-3 has 4 grid points, so that only theone image capturing device may be used as the image capturing source.

If there is no image capturing device with the grid point number of thecovered grid points being equal to 12, the image capturing device withthe largest grid point number of the covered grid points is selected asthe image capturing source, and it is confirmed that the photographingrange of the image capturing source may cover the projection ranges ofall of the projection devices. If the photographing range of the imagecapturing source does not cover the projection ranges of all of theprojection devices, the image capturing device with the second largestgrid point number of the covered grid points is further selected as theimage capturing source. Taking the embodiment shown in FIG. 4A to FIG.4I as an example (with reference of Table 1), the image capturingdevices 120-2 and 120-3 (which cover the largest grid point number ofthe grid points) are selected as the image capturing sources, and thephotographing ranges of the image capturing devices 120-2 and 120-3 maycover the projection ranges of all of the projection devices 110-1 to110-3.

In addition, the processor 130 may also determine the image capturingsource for image blending based on the grid point number, the grid pointpositions, and the image capturing quality included in each imagecapturing result. For example, it is assumed that the image capturingdevices with the largest grid point number of the grid points that arefound based on the image capturing results are A, B, and C, and thephotographing ranges of the image capturing devices A and B cover theprojection ranges of all of the projection devices, and thephotographing ranges of the image capturing devices A and C also coverthe projection ranges of all of the projection devices, the imagecapturing sources may be determined as the image capturing devices A andB or the image capturing devices A and C according to the imagecapturing quality of the image capturing devices B and C.

In addition, when the processor 130 determines that at least one imagecapturing device serving as the image capturing source is abnormal inimage capturing, the image capturing device determined to be abnormal inimage capturing is disabled, and at least one image capturing device isselected from other unselected image capturing devices to update theimage capturing source. The image capturing device that may cover theprojection ranges of all of the projection devices is selected withpreference, so that the photographing range of the updated imagecapturing source may cover the projection ranges of all of theprojection devices.

FIG. 5A and FIG. 5B are schematic diagrams of activating a backup deviceaccording to an embodiment of the invention. In the embodiment, threeprojection devices 110-1 to 110-3 and three image capturing devices120-1 to 120-3 are taken as an example for description. The projectiondevices 110-1 to 110-3 respectively project patterns to obtainprojection images 501-503. It is assumed that the image capturingdevices 120-2 and 120-3 are used as main image capturing sources, andthe image capturing device 120-1 is not activated. The image capturingdevices 120-2 and 120-3 respectively obtain image capturing results B1and B2. When it is determined that the image capturing device 120-2 isabnormal in image capturing, the image capturing device 120-1 isactivated to obtain an image capturing result B3 through the imagecapturing device 120-1.

In addition, when it is determined that the photographing range of theupdated image capturing source cannot cover the projection ranges of allof the projection devices, the processor 130 may further issue a warningnotice. For example, the warning notice is a sound signal, a textsignal, an image signal, or a flashing light signal, etc. Accordingly,the user is notified to send the projection system for repair.

In summary, the invention uses fully automated software and algorithmsto automatically set effective ranges of the image capturing devices forcapturing images, so as to define whether there is a phenomenon of imageoverlap. In the above embodiments, the image capturing range isidentified through projected patterns, and the effective ranges arecalculated and then selected with preference for usage, which may beused for calculations required for automatic blending. In this way, thenumber of images obtained by the image capturing devices by capturingthe projected patterns is reduced, so as to improve a speed of the imagecapturing process, and avoid a problem of being unable to maintainblending and merging due to environmental influences or failure of theimage capturing device when performing image recognition and calculationrequired for automatic blending and merging.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform or to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to best explain the principles of the invention andits best mode practical application, thereby to enable persons skilledin the art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to particularly preferredexemplary embodiments of the invention does not imply a limitation onthe invention, and no such limitation is to be inferred. The inventionis limited only by the spirit and scope of the appended claims.Moreover, these claims may refer to use “first”, “second”, etc.following with noun or element. Such terms should be understood as anomenclature and should not be construed as giving the limitation on thenumber of the elements modified by such nomenclature unless specificnumber has been given. The abstract of the disclosure is provided tocomply with the rules requiring an abstract, which will allow a searcherto quickly ascertain the subject matter of the technical disclosure ofany patent issued from this disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Any advantages and benefits described may notapply to all embodiments of the invention. It should be appreciated thatvariations may be made in the embodiments described by persons skilledin the art without departing from the scope of the present invention asdefined by the following claims. Moreover, no element and component inthe present disclosure is intended to be dedicated to the publicregardless of whether the element or component is explicitly recited inthe following claims.

What is claimed is:
 1. A projection system, comprising: a plurality of projection devices, a plurality of image capturing devices, and a processor, wherein: the processor is coupled to the projection devices and the image capturing devices, the processor is configured to drive the projection devices one-by-one to project a pattern, drive the image capturing devices to capture the pattern projected by each of the projection devices, so as to obtain a plurality of image capturing results corresponding to the image capturing devices, and select at least one of the image capturing devices to serve as an image capturing source for image blending based on the image capturing results.
 2. The projection system as claimed in claim 1, wherein the processor is configured to drive the image capturing devices to capture the projected pattern respectively or simultaneously after one of the projection devices projects the pattern.
 3. The projection system as claimed in claim 1, wherein the pattern comprises at least one grid point; and the processor is configured to identify a grid point number of the at least one grid point and a grid point position of the at least one grid point comprised in each of the image capturing results, and select at least one of the image capturing devices to serve as the image capturing source for image blending based on the grid point number and the grid point position, wherein a photographing range of the selected at least one of the image capturing devices covers the most at least one grid point.
 4. The projection system as claimed in claim 3, wherein the processor is configured to select the at least one of the image capturing devices to serve as the image capturing source for image blending based on the grid point number and the grid point position of the at least one grid point comprised in each of the image capturing results and on image capturing quality.
 5. The projection system as claimed in claim 1, wherein when determining that the at least one of the image capturing devices serving as the image capturing source is abnormal in image capturing, the processor is configured to disable the at least one of the image capturing devices determined to be abnormal in image capturing, and select at least one image capturing device from other unselected image capturing devices to update the image capturing source.
 6. The projection system as claimed in claim 5, wherein the processor is configured to issue a warning notice when determining that a photographing range of the updated image capturing source is unable to cover projection ranges of all of the projection devices.
 7. The projection system as claimed in claim 1, wherein a number of the projection devices is at least two, a number of the image capturing devices is at least two, and the number of the projection devices and the number of the image capturing devices are the same or different.
 8. The projection system as claimed in claim 1, wherein one of the image capturing devices is disposed on one of the projection devices.
 9. A method for selecting an image capturing number for image blending, the method comprising: driving a plurality of projection devices one-by-one to project a pattern; driving a plurality of image capturing devices to capture the pattern projected by each of the projection devices, so as to obtain a plurality of image capturing results corresponding to the image capturing devices; and selecting at least one of the image capturing devices to serve as an image capturing source for image blending based on the image capturing results.
 10. The method for selecting the image capturing number for image blending as claimed in claim 9, wherein driving the image capturing devices to capture the pattern projected by each of the projection devices comprises: driving the image capturing devices to capture the projected pattern respectively or simultaneously after one of the projection devices projects the pattern.
 11. The method for selecting the image capturing number for image blending as claimed in claim 9, wherein the pattern comprises at least one grid point, and selecting the at least one of the image capturing devices to serve as the image capturing source for image blending based on the image capturing results comprises: identifying a grid point number of the at least one grid point and a grid point position of the at least one grid point comprised in each of the image capturing results; and selecting the at least one of the image capturing devices to serve as the image capturing source for image blending based on the grid point number and the grid point position, wherein a photographing range of the selected at least one of the image capturing devices covers the most at least one grid point.
 12. The method for selecting the image capturing number for image blending as claimed in claim 11, wherein selecting the at least one of the image capturing devices to serve as the image capturing source for image blending based on the image capturing results further comprises: selecting the at least one of the image capturing devices to serve as the image capturing source for image blending based on the grid point number and the grid point position of the at least one grid point comprised in each of the image capturing results and on image capturing quality.
 13. The method for selecting the image capturing number for image blending as claimed in claim 9, the method further comprising: when determining that the at least one of the image capturing devices serving as the image capturing source is abnormal in image capturing, disabling the at least one of the image capturing devices determined to be abnormal in image capturing, and selecting at least one image capturing device from other unselected image capturing devices to update the image capturing source.
 14. The method for selecting the image capturing number for image blending as claimed in claim 13, wherein after updating the image capturing source, the method further comprises: issuing a warning notice when determining that a photographing range of the updated image capturing source is unable to cover projection ranges of all of the projection devices.
 15. The method for selecting the image capturing number for image blending as claimed in claim 9, wherein a number of the projection devices is at least two, a number of the image capturing devices is at least two, and the number of the projection devices and the number of the image capturing devices are the same or different.
 16. The method for selecting the image capturing number for image blending as claimed in claim 9, wherein one of the image capturing devices is disposed on one of the projection devices. 